New York City hasn’t built a new line since 1932, and after seeing these pictures one can begin to understand why. The $17 billion project to create the Second Avenue Subway is a massive undertaking – and that’s an understatement.

Sometimes referred to as “The Line That Time Forgot,” the Second Avenue Subway has been planned and occasionally worked on since the 1920s. The many delays are due to numerous reasons, but if things keep moving along a new 8.5-mile tunnel will stretch from Hanover Square at the tip of Manhattan up to 125th Street in Harlem. On all those transit maps around New York, the new line will be known as the T service.

Get an idea of just how much goes into unearthing a new line in the pictures below.